In the majority of products installing a cellular module of the GSM/GPRS/3G/4G type, the selection of the GSM (PLMN) carrier is processed automatically by the radio module. In this automatic mode, the selection of the GSM carrier is completely managed by the radio module. This solution is practical since it deals with situations such as the search for an operator in a new country (roaming) or makes it possible to pass to another operator when coverage is lost.
Manual or automatic selection according to rules fixed by the main operator is not the only solution.
In the prior art the French patent FR 2949179 is known, which describes a method for establishing a connection between a mobile communicating object and a mobile communication network where the communicating object has list containing a given number of preferred mobile communication networks with which the object can connect. This list comprises a plurality of sub-lists of networks (PLMNs) hierarchized so that the networks (PLMNs) included in a sub-list are preferred to all the networks included in the sub-lists of higher rank.
This method of the prior art comprises the steps consisting of:                detecting available networks        if at least one of the detected networks belongs to the list, connecting to the preferred network among the detected networks, the preferred network being the network belonging to the sub-list with the lowest rank        if the preferred network among detected belongs to a sub-list of rank n higher than or equal to 2:                    i) seeking the availability of new networks at regular intervals;            ii) if one or more networks belonging to one of more sub-lists of rank lower than or equal to n are detected as being available, connecting to the detected network belonging to the sub-list of lowest rank.                        
In the prior art the American Patent Publication US 2009/0207812 is also known, describing a method for switching a device from a source network to a target network, the source network being one from a WiMAX network and a 3GPP network and the target network being another WiMAX network and the 3GPP network, comprising reception information coming from the device on the source network and on the target network. The information received from the device may be supervised in order to determine whether the parameters of the network of the source have passed an intercell transfer threshold. The information received from the device may also be checked in order to determine whether the parameters of the target network are suitable for a transfer.
The international patent WO 2008/000914 is also known, proposing a solution for measuring an adjacent cell and signaling in a multiple radio access technology (RAT) environment.
User equipment (UE) carries out measurements of adjacent cells with an inter-radio access technology (RAT) during a standby mode of the UE. The results of inter-RAT measurements may be stored in an internal memory of the UE during the standby mode. When the UE triggers an establishment of the connection, a report on inter-RAT measurements containing results of inter-RAT measurements obtained during the standby mode is sent to the network when the connection is established. Consequently the inter-RAT measurement information is immediately available for a network decision at the commencement of the connected mode. For example, an inter-RAT inter-cell transfer may be decided on and implemented without delay, on the basis of the inter-RAT measurement made in advance during the standby mode and signaled when the connection is established.
The prior art also comprises the European patent EP 1986372 describing a method and apparatus for supporting a transfer between heterogeneous access networks, in which user equipment information and the candidate access network information are detected, a transfer decision is evaluated on the basis of the information on the user equipment and the candidate access network information, and an access network is chosen from a plurality of candidate access networks on the basis of the inter-cell transfer decision.
The international patent WO 2005/115039 relates to a method for transferring a communication established between a radio-communication terminal and a first radio-communication system, to a second radio-communication system. For transmitting information, the first radio-communication system uses a first radio-communication standard and the second radio-communication system uses a second radio-communication standard. The radio-communication terminal monitors not only the adjacent radio cells of the first radio-communication system but also the adjacent radio cells of the second radio-communication system by measurements and transmits the valid measured signal levels of the monitored radio cells of the first and second radio-communication systems to a monitoring device on the network side. In the case where the measured signal levels are occasionally not formed during the monitoring of the radio cells by the second radio-communication system, the radio-communication terminal transmits predetermined signal levels to the monitoring device. The radio-communication terminal uses a symbol that enables the network to distinguish the valid measured signal levels from the predetermined signal levels. When the communication transfer is demanded by the monitoring device, only the valid measured signal levels are taken into consideration.
The solutions of the prior art lead to a selection of the network of the PLMN according to criteria taking into account mainly the commercial agreements between the operators and the power of the radio signal received locally.
However, for some applications, other criteria are preponderant: availability of certain accesses (TCP ports for example) for specific data transmissions. By way of example, such applications concern the remote transmission of medical data, for example, by a patient equipped with biomedical sensors, such as a health parameter measurement apparatus (weight, pulse, blood pressure, blood oxygenation level, glucose monitor), automatically triggering the sending of digital data via the mobile network to a server center.
The selection made in accordance with the prior art does not make it possible to favor the most appropriate network and this may lead to serious situations of unavailability of the service because of an inappropriate selection of the network.
In some cases, the radio module is registered with the GSM networks on which:                Only the GSM voice service is adopted when the product requires a GPRS service. GPRS is not supported by the operator.        GPRS is adopted, but access to the APN to recover an IP address is not possible (temporary unavailability, agreement problems, etc.).        An IP address is attributed to the product, but IP communication is not possible (defective equipment on the pathway (router) etc.).        The charging rate is not suited to the application.        Maintenance operations leading to the unavailability of the service are planned.        The network chosen is the one that has the strongest signal but is also the one that is the most saturated.        The network chosen was indeed the most suitable at the time of choice, but the quality of the radio signal has dropped without the module changing network.        
Registration to these networks according to the solutions of the prior art is therefore a problem when the product needs GSM/GPRS/3G/4G access.
Moreover, in the solutions proposed in the prior art, it is the server that controls the selection of the network from criteria predefined in this server.